LM1036 for subwoofer volume control?

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My car stereo has an extra stereo line level output, but it does not have any options to adjust the line output volume independently of the other speakers.

I would like to use a factory style lamp dimmer knob mounted in the car to control the sub woofer volume. This dimmer contains a single 50K linear pot.

I am pretty sure I cannot use the pot directly due to its physical location, linear taper, and high resistance. I will probably need to hook it to a voltage controlled pot.

I did find the LM1036, which looks like it would work perfectly with no modifications with my current pot. But from what I have read here, most people dislike its low SNR.

Does the relatively poor SNR of the LM1036 really matter in an automotive sub woofer application? According to my car stereo's manual, it only has a SNR of 80db to begin with.

Or do you have any suggestions on what else I could use? I have been searching through datasheets for days, and all I find are digitally controlled chips.

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I forgot to mention, I did also run across the TDA1524A which has similar specs, but might be better suited for my purpose because it allows higher input voltages.

[pacificblue]

Replacing the pot is not an option?

[paulb]

I would use the LM1036. I would suggest the SSM2018T as well, but it may be on the verge of being discontinued although Digikey still has stock.

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Originally posted by pacificblue
Replacing the pot is not an option?

My goal is to make it look "stock" so I am limited by what the car company used.

This is what I found at the junk yard:


Now, I guess I could use the seat warmer controls with an up/down button digital audio pot, but I really prefer analog knobs for volume controls.

And if I am going to use the dimmer knob, I am stuck with a 50K linear pot. I did crack open the unit, and the pot looks like it would be difficult to change (if I could even find units of the same physical dimensions).

[theAnonymous1]

BMW?

My 325i just got hit yesterday while parked in front of my apartment.

Do a "law faked" mod on the linear pot and use a buffer before/after if necessary.

http://sound.westhost.com/pots.htm#chg-law

[pacificblue]

The LM1036 seems to be your best option then.

The alternative would be to mix the two signals to a mono signal and then follow theAnonymous1's tip.

[Swap_File]

Yeah, 1996 BMW 318ti. I have three empty button holes (no Traction Control, Fog Lights, or Heated Seats), so I am filling them with more useful buttons.

ASC button will be a garage door opener, dimmer knob will be a sub volume control, and I think I might get the factory fog light kit.


Thanks for link, I looked through the ESP site a bit, and never ran across that information.

The only issue with using the pot directly is that I cannot easily mount it in a steel box like I can with the chips, and I am not sure what kind of interference I am going to be dealing with in the car.


I think I am just going to order the parts to try it all three ways. LM1036, TDA1524A, and mixing it to mono and using the pot directly. I need to make the $25 minimum order from digikey anyway.